Agroforestry and conservation

A new paper out in Biodiversity and Conservation presents a review of how smallholder agroforestry contributes to the conservation of tropical tree species.1 That can seem a funny way to look at it, I admit that even as a co-author. The more obvious question might have been to ask how tree conservation efforts can contribute to smallholder agroforestry, and that has indeed been covered in another paper by some of the same authors. What we were at least partly trying to do in this paper is to make the point to the more general tropical biodiversity community that farmers and cultivated landscapes potentially have a role in conservation.

Potentially being the operative word. Because it’s not automatic. In particular, the paper highlights three areas where we need to do some more work in order to make sure that the potential is realized.

1. Although agroforestry systems can be highly diverse in tree species, this may be transitory, for example as remnant forest trees in farmland die. We need to know how to promote connectivity among low density trees in agroforestry systems in order to support conservation in farm landscapes.

2. Tree cultivation in agroforestry systems (or in plantations) may well support the conservation of nearby trees in natural forest by taking pressure off the resource base, as the conventional wisdom has it. But it may not. In fact, we know little about the link between the two, and there are reasons to think this link is often negative rather than positive for conservation.

3. Ex situ seed storage may not be much of an option for trees because of the high costs of regeneration of stored seed. Do ex situ genebanks lead to a false sense of security about what is conserved? What sorts of partnerships are necessary for genebanks to really come through?

Funnily enough, another paper just out reviews the conservation and use of a particular tropical agroforestry tree, Bactris gasipaes, or the Peach palm.2 The authors recommend smaller, more carefully chosen and better characterized ex situ collections, which fits in with the third point.3 But not only:

On-farm conservation could be an appropriate alternative for in situ conservation of wild populations, particularly if high levels of diversity are maintained in nearby cultivated populations and these are genetically close to wild populations (Hollingsworth et al. 2005).

As the two previous points suggest, that “could” will need to be deconstructed a bit if a truly effective conservation strategy is to emerge.

But the paper doesn’t stop there. I was particularly interested in the observations that processing and value addition are “virtually non-existent,” and that “40-50% of peach palm production never reaches the market and is either fed to farm animals or wasted.” Plenty of scope for conservation of this particular agroforestry species to contribute to smallholder systems, and perhaps vice versa.

4 Replies to “Agroforestry and conservation”

Luigi: Interesting new ideas. BUT agroforestry systems are now being used to expand the already vast coverage of protected areas into farming. If trees and farms can co-exist – and they can – then let farmers back into Yellowstone-style protected areas that quite unnecessarily exclude farming. Until that is done, then keep out of farms.
I have an aversion to the terminology`agroforestry’ – with its implication of forests and timber extraction. Why not use the term agri-arboriculture? Yen used arboriculture for the forest gardens around the Pacific. It recognizes that fruits, nuts, spices, firewood and lots more are produced.
Also, for circa-situm conservation you can only be talking of indigenous species. This is simply silly. Farmers need oranges, guava, avocado, mango and lots more wherever they are, not just around centres of origin. Why restrict farmers’ options to growing trees close to wild stands and all those native pests and diseases.
I would never consider Peach palm as a tree – it’s a multi-stemmed palm. The big collection at CATIE in Costa Rica was maintained as a production plot – fruits and palm hearts, given to the workers as a treat. An unmanaged germplasm collection turned into a jungle. As it was behind the Director’s house, he had it cleared as a snake menace (very many coral snakes loved it).

Responding to Dave as the lead author of the first paper that Luigi mentioned:

Dave, one of the points we wish to make with the agroforestry/conservation paper is that you cannot really consider farms and forests, and conservation in both, independently.

People have different perceptions of the term agroforestry and it has some hang ups (especially outside the tropics), but in our case we just mean ‘trees on farms’.

Tropical smallholders’ often rely heavily for their incomes on exotic tree fruits and other tree commodity crops, and over hundreds of years some have developed landraces worth of conservation in exotic locales (that would come for us under ‘ex situ’ rather than ‘circa situm’…, still possibly in farmland…) – cacao would be a good example.

However, the ‘conservation value’ of many exotic tree populations is probably over-estimated in many cases – they do not represent genuine landraces and are often lower performance and mal-adapted, as we mention in the paper.

That is not to say, of course, that exotic trees do not have important livelihood value (and sometimes their own particular connected problems), as the paper relates…

Ian: Thanks. One problem I have is the Springer paywall, so I don’t have the details of what you say. Conservation value is not what anyone should be selling to poor farmers, who are interested in food and market crops.
I think you are dead wrong on exotics being `often lower performance and mal-adapted.’ Purseglove in 1968 noted that the main areas of production of major economic crops are usually far removed from areas in which they originated. I would add to major crops also most fruit trees and plantations crops, and even plantation forest trees and certainly street ornamentals (for example, Jacaranda in Kenya and Queensland). And Purseglove gave a reason: indigenous crops are constrained by co-evolved pests and diseases. They are therefore mal-adapted to biotic constraints compared to exotics. The much-used term and concept of `locally adapted’ is not adequate, indeed is deceptive if related to agronomic performance. Distinction must be made for biotic constraint, where an indigine may fair badly, and abiotic constraints, where an native variety may over time have become locally adapted to, say, photoperiod, or rainy season. But so may an exotics from homo-climes and similar latitudes but without the constraints of local pests and diseases. And as for local evolution, most economic trees are clonally propagated and not subject to evolutionary change (somebody once claimed that all exotic mangosteens were from one source). Of course, under changing conditions, the exotic may be constrained by a narrow genetic base. But that is easily solved by moving varieties from similar abiotic conditions (and we have a vast supply of samples in genebanks and orchard collections as at CATIE as sources).
I was a tiny part of this approach to crop introduction at CIAT, where Peter Jones was developing `Flora Map’ and from where Jennings and Cock in 1977 had recommended that national strategy should emphasize the production of introduced food crops (my figures showed nearly 70% of crop production in Latin America and Africa is from such introduced crops). CIAT should blow its trumpet with vigour on introduced crops – they were there from the start.
One of the great success stories of global agriculture was (and is) the USDA introduction of everything from everywhere to almost everywhere – a trial-and-error performance over more than a century that worked superbly (but they got the essential quarantine right).